1. Field of the Invention
The present invention relates generally to exhaust fans and, more particularly, to exhaust fans for removing airborne materials.
2. Related Art
Stationary and portable fans have been known for years and have been used for numerous applications. One use of exhaust fans of particular pertinence to the present invention is the removal of airborne contaminants from a localized area. As used herein, the term airborne material refers to any particles, fumes, dust, chemicals or other materials that are suspended in the air.
There are many drawbacks to traditional exhaust fans used for removing various airborne materials in different applications. In particular, there are significant drawbacks associated with conventional exhaust fans that are used for removing from a localized area overspray from spray painting, airborne dust from surface sanding, airborne chemicals from painting, varnishing, staining and similar activities.
One such drawback is that conventional exhaust fans expose the air traveling through the fan to events that can ignite flammable airborne materials. Thus, conventional exhaust fans are generally inappropriate to be used to remove safely from a localized area air having flammable or combustible airborne materials.
Another drawback is that currently available exhaust fans do not protect the internal components of the fan from the air passing therethrough, resulting in an accumulation of materials on such internal components. Certain airborne materials such as paint overspray readily accumulate on the internal components of the fan such as the fan blade, blade shaft, grating, electrical components, etc. This requires conventional fans to be periodically disassembled and cleaned. Unfortunately, such conventional fans cannot be disassembled. As result Oftentimes, an exhaust fan used in such applications must be discarded once a significant amount of material accumulates on the fan components, adversely affecting the operating performance of the fan.
Another significant drawback to conventional exhaust fans is that they often do not clean the air before releasing it into the surrounding environment. That is, the airborne materials are not removed from the air. As a result, such conventional exhaust fans are unsuitable for use in may communities in which clear air standards have been established.
What is needed, therefore, is an exhaust fan that can safely remove airborne contaminants from a localized area without damaging the exhaust fan itself or releasing the materials into the surrounding environment.
The present invention is directed to a portable, light-weight exhaust fan that can be easily and quickly carried to and set up in a localized area to safely, efficiently and substantially remove airborne materials thereby overcoming the above and other drawbacks of conventional exhaust fans. Exhaust fans in accordance with aspects of the present invention may be used to ventilate a localized area such as an enclosed room and may be placed in any aperture such as a window or doorway to remove substantially all airborne material from the air passing therethrough, and to exhaust filtered air directly or indirectly to the surrounding environment.
Aspects of the present invention are directed generally to an exhaust fan constructed such that air traveling along an exhaust path through the fan is prevented from contacting components of the fan that can be damaged by exposure to the airborne materials. This enables the exhaust fan to efficiently remove airborne materials from a localized area while preventing the same materials from adversely affecting the operation of the fan. This has particular utility in applications wherein the airborne material such as paint overspray adheres readily to surfaces. By preventing the accumulation of debris on internal fan components, the fan operates with greater efficiency for longer periods of time, does not require the extensive periodic cleaning, and has a significantly longer operational life. The fan components that necessarily come into contact with the air; that is, the interior surface of the exhaust chamber and the vanes of the fan, are preferably accessible and/or removable to facilitate cleaning.
A number of aspects of the invention are summarized below, along with different embodiments that may be implemented for each of the summarized aspects. It should be understood that the summarized embodiments are not necessarily inclusive or exclusive of each other and may be combined in any manner in connection with the same or different aspects that is non-conflicting and otherwise possible. These disclosed aspects of the invention, which are directed primarily to exhaust fans, are exemplary aspects only and are also to be considered non-limiting.
In one aspect of the invention a portable exhaust fan for removing airborne materials from a localized area is disclosed. The fan includes a housing having an inlet opening and a discharge opening and an air passageway between the inlet and discharge opening. A centrifugal blower unit mounted such that at least rotating blades of the blower unit are located within the air passageway to draw air into the inlet opening and to cause the air to travel through the air passageway and exit through the discharge opening. Importantly, substantially all of the airborne material is removed from the air prior to the air traveling through the air passageway. In addition, the air traveling through the air passageway does not contact surfaces or components that are adversely affected by coming into contact with the airborne material.
In one embodiment, the fan components include electrical components. In such an embodiment the exhaust fan further includes an electrical box constructed and arranged to prevent exposure of said electrical components housed therein from airborne materials traveling through the air passageway. For example, in one particular embodiment, the electrical box is secured within the housing and is substantially impenetrable by the air traveling through the air passageway. Alternatively, the electrical box is secured to an exterior surface of the housing. Preferably, the electrical box is an explosion proof electrical box.
In the same or another embodiment of this aspect of the invention, the exhaust fan components further include electrical wiring. In such embodiments, the exhaust fan further includes sealed conduits through which said electrical wiring travels within said housing, wherein said conduits are substantially impermeable to the airborne materials that are being removed from the localized area.
In another aspect of the invention, a portable, light-weight exhaust fan that can be easily and quickly carried to and set up in a localized area to safely, efficiently and substantially remove airborne materials including flammable airborne materials, is disclosed. The exhaust fan is constructed such that air traveling along an exhaust path through the fan is prevented from contacting components of the fan that can be damaged by exposure to the debris and that can ignite flammable debris in the air. This prevents the airborne materials from accumulating appreciably on the exhaust fan components such as the blower fan blade. In one application the airborne materials comprise paint overspray; in others, hazardous airborne materials; in still others, flammable materials.
In specific embodiments, the exhaust fan is constructed and arranged such that the exhaust path prevents air from coming into contact with those fan components that are incendiary promoters. This includes, for example, high temperature surfaces, electrical components, etc. Such electrical components may further prevented from exposure to the localized environment to further insure they do not ignite the flammable airborne materials before passing through the exhaust fan.
In one embodiment of this aspect of the invention, the internal components of the exhaust fan that are exposed to the air passing therethrough are accessible and removable. In another embodiment, the fan also includes an inlet filter located adjacent to an inlet opening of the exhaust path. The filter is constructed and arranged to remove at least those airborne materials that can accumulate on or otherwise damage the internal fan components. Preferably, the fan also includes an exhaust filter located adjacent to a discharge opening of the in the exhaust path. Such an exhaust filter can be constructed and arranged to remove the airborne materials that may damage the environment.
The exhaust fan also may include a flexible exhaust tube having a proximate end configured to be coupled to the inlet opening of the exhaust fan and a distal end for placement in a localized area for receiving air to be filtered exhausted. In such embodiments, the exhaust fan can be placed in a window or other aperture opening to the surrounding environment while the distal end of the tube can be place in the localized environment for receiving the air to be exhausted. This enables the exhaust fan to be used to remove airborne debris of form a localized environment that does not have a window or other aperture to the surrounding environment.
In a still further aspect of the invention, an exhaust fan for removing airborne materials from a localized environment is disclosed. The fan includes a housing having an inlet opening and a discharge opening and an air passageway between the inlet and discharge openings. A centrifugal blower unit including an enclosed motor and a fan blade removably mounted on a shaft extending therefrom is also included. The blower unit is mounted within the air passageway to draw air into the inlet opening and to cause the drawn air to travel through the air passageway and to exit through the discharge opening. Also included is an electrical box mounted on an exterior surface of the housing. The electrical box is substantially impenetrable by air, fluids and gases. Two filters are also included in the exhaust fan. An inlet filter located adjacent to an inlet opening of the in the exhaust path is constructed and arranged to remove from the air passing therethrough at least those materials that can accumulate on or otherwise damage the internal fan components. An exhaust filter located adjacent to a discharge opening of the in the exhaust path, constructed and arranged to remove from the air passing therethrough any airborne materials that may damage the environment.
Various embodiments of the present invention provide certain advantages and overcome certain drawbacks of the conventional self-test techniques. Not all embodiments of the invention share the same advantages and those that do may not share them under all circumstances. This being said, the present invention provides numerous advantages including the noted advantage of providing safe and efficient removal of airborne materials including hazardous materials from the localized air. These and other features and advantages of the present invention as well as the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings.